The Northern Patrol, also known as Cruiser Force B and the Northern Patrol Force, was an operation of the British Royal Navy during the First World War and Second World War. The Patrol was part of the British "distant" blockade of Germany. Its main task was to prevent trade to and from Germany by checking merchant ships and their cargoes. It was also to stop German warships, raiders and other German naval ships from leaving the North Sea for the Atlantic Ocean or entering the North Sea from the Atlantic, protect Shetland against invasion and to gather intelligence from intercepted neutral ships. The Northern Patrol operated under the command of the Grand Fleet during the First World War. At first, Edgar-class cruisers were used but these were not built for the seas around Scotland in winter and were replaced by civilian ships pressed into service as Armed Merchant Cruisers. In the Second World War the Northern Patrol was commanded by the Home Fleet in the. Perhaps the Northern Patrol's most famous action was the loss of the armed merchant cruiser On 23 November 1939. Captain Edward Kennedy RN, commander of the ANC decided to fight the 11-inch gun German capital ships Scharnhorst and Gneisenau, rather than surrender as demanded. The crew of Rawalpindi managed to inflict splinter damage on Scharnhorst during a short engagement, before being sunk only a few survivors being rescued by the Germans. Background Blockade, 1815–1914 For much of the nineteenth century, the Admiralty and much of the navy took it that the main aim was to engage and defeat an opposing fleet. In 1908 war orders to the Channel Fleet were that Success in this object would guarantee command of the English Channel and the North Sea, secure British trade and territory and allow the Expeditionary Force to reach France. The Admiralty expected that the German fleet would sally forth, soon after the declaration of war to contest British command of the sea. An alternative to decisive battle was the close blockade of opposing ports as occurred during the Napoleonic Wars (1803–1815). Swift-sailing frigates cruised off French ports, backed by bigger ships out to sea. The blockading ships were almost immune to attack and with no need to return to port to refuel. The advent of steam power required more frequent returns to port for coal and after 1900, the risks to blockading ships multiplied with